A preprint is the authors' version of a manuscript before it has been submitted for publication proceeds. Preprints have not gone through the peer-review process that published journal articles undergo. Since peer review can take 3 to six months, preprints are valuable in fields that develop rapidly. Preprints are freely available on several preprint servers.

• medRxiv: Accepts manuscripts from all aspects of medicine, nursing, and health sciences. Screens submissions for offensive and/or non-scientific content and for material that might pose a health risk. Founded by Cold Spring Harbor Laboratory, Yale University, and BMJ in 2019.
• ​bioRxiv: Accepts manuscripts from the life sciences. Screens submissions for offensive and/or non-scientific content and for material that might pose a health or biosecurity risk. Maintained by Cold Spring Harbor Laboratory and founded in 2013.
• arXiv: Though focussed on physics, arXiv's contents include quantitative biology, materials science, robotics, machine learning, AI and other topics relevant to the life and health sciences. Managed by Cornell University and founded in 1991 at Los Alamos National Laboratory.